The hexagonally organized mammalian urothelial cell membrane is being studied by a combination of electron microscopic and biophysical methods. It is being studied by freeze-fracture-etch electron microscopy utilizing special fast-freezing techniques with freeze-fracture-etch methods involving fracturing and replication at different temperatures. The biophysical properties of the membrane are being studied by fluorescent probe and scanning microcalirometric methods. The membrane is also being studied by both wide angle and small angle x-ray diffraction methods. Similar studies are also being conducted of other membranes including those of erythrocytes and the purple membrane of Halobacterium halobium. All of these membranes are being analyzed by deposition on glass surfaces before fracturing and replication in order to conduct morphometric analyses of intramembrane particles. Low dose electron microscopic studies of negative stained and glucose embedded urothelial membranes are being conducted utilizing 3D computer analysis.